Green vat dye and process of making same



Patented Nov. 4, 1924.

UNITED STATES PATENT OFFICE.

IAUL NA'WIASKY, OF LUDW IGSEAIEN-ON-THE-RHINE, GERMANY, ASSIGZNOR TO BADISCHE ANILIN- 8c SODA-FABBIK, OF LUDWIGSHAFEN-ON-THE-RHINE, GER- MANY.

GREEN VAT DYE AND PROCESS OF MAKING SAME.

K0 Drawing.

To all whom it may concern:

Be it known that I, PAUL NAWIASKY, a citizen of Austria, residing at Ludwigshafen-on-the-Rhine, Germany, have invented new and useful Improvements in Green Vat Dyes and Processes of Making Same, of which the following is a specification.

As is known, dibenzanthrone can be transformed, by nitration, into a derivative which, either without further treatment or after reduction, can be employed as a vat dyestufi producing valuable green dyeings. The shades thereof, however, are rather dull.

The dyestuil may be recrystallized from nitrobenzene without however substantially altering by this treatment the shade of the dyeings produced and the same dyeings are obtained when subjected to nitration a substantially pure dibenzanthrone such as may be produced by either re-vatting raw dibenzanthrone or effecting the alkali melt of benzanthrone in the presence of aniline or other diluents, as described in the German Patent 290,079.

Notwithstanding these facts, the nitration roduct of dibenzanthrone, according to this invention, is not uniform but is capable of being separated into a very valuable clear green vat dyestuif on the one hand, and a greenish gray dyestufl, on the other. The separation ma be effected by dissolvin the nitration ro not in concentrated sul uric acid, and ractionally precipitating it therefrom by carefully ad ing pro or diluents, for example dilute sulfuric aci The valuable clear green dye is precipitated thereby. It is distinguished from the raw product, apart from its clearer hue, by a su erior strength and also by its properties. ile the raw nitration product dissolves in concentrated sulfuric acid with a dull bluish violet color, the new roduct dissolves therein bright bluish vio et. The new product, after being treated at 180 degrees cetigrade, for 6 hours with its own weight of anhydrous aluminum chlorid and twenty times its weight of nitrobenzene, still gives green Application flied December 12, 1923. Serial No. 680,262.

dyeings which on exposure to dilute hypochlorite-solution turn black, while the raw nitration product, after the same treatment, dyes bluish gray which remains practicall or entirely unaltered by a treatment wit hypochlorite.

The following example will serve to further illustrate the invention but the latter is not restricted to these examples. The parts are by weight.

- Example 1.

100 parts of nitrated raw or pure dibenzanthrone, produced according to patent 796,393, dated August 1, 1905, are dissolved in 1,000 parts of sulfuric acid of 66 degrees Baum, then 500 parts of sulfuric acid of 60 degrees Baum strength are slowly added,

while stirring, at between about 60 degrees tion.

Example 2.

505 parts of nitrated dibenzanthrone are dissolved in 700 arts ofconcentrated s 1- furic acid of 66 egrees Baum. The so ution is heated to about 60 degrees centigrade, then parts of water are allowed to run in slowly, the temperature bein ke t below 75 degrees centigrade. Fina ly t e solution is cooled, filtered and worked up as described in the foregoing example.

Glacial acetic acid may be used instead of water, 25 parts being suflicient under the same conditions.

Now what I claim is: p

A new form of nitrated dibenzanthrone in which it dissolves in concentrated sulthe action of dilute hypochlorite solution furic acid with a pure bluish violet color turn black. 10 and in which form 1t dyes cotton clear en In testimony whereof I have hereto set shades and which new form after fling my hand.

treated forefi hours at 180 degrees'centl- PAUL NAWIASKY. grade with its own weight of anhydrous Witnesses: aluminum chlorid and 20 times its wexght of Wnmmm: Scams, nitrobenzene, gives green dyeings WhlOll by ARTHUR DENONVILLE.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1.518.851, granted Nos-Huber 4, 1924, upon the application of Paul N'awiasky, of Lmlwigshafen-on-the-Rhine. Germany, for an improvement in Green Vat Dyes and Processes of Making Same, an error appears in the printed specification requiring cnrrectiun as follows: Page 1. line 81. for the numeral 505'read 60; and that the said Letters Patent should be read with this cm-revt-ion therein that the same may conform to the remrd of the case in the Patent Oflice.

Signed and sealed this 27th day of January, A. I). 19-25.

' KARL FENNDNG,

Acting Commmwner of Patents. 

